Researches On The Volume Of Ballast Water Discharged By Chinese Entry And Exit Vessels And Its Advanced Oxidation Emergency Treatment Technology

Vessel's ballast water is the main way for the transfer of marine non-indigenous species(NIS).The International Convention for the Control and Management of Vessel's Ballast Water and Sediments,adopted by the International Maritime Organization(IMO),has taken effect on September 8,2017.Based on the Convention,all vessels going to enter the sea areas of States Parties are required to install ballast water treatment systems approved by IMO,and the treatment results of ballast water must meet the D2 standard requirements.However,owing to the various water qualities in different sea areas,there is still no a treatment system that could be applicable to all sea areas until now.The volume and features of the discharged ballast water are the fundamental elements for the risk assessment of marine environment.However,it is difficult to obtain the volume of ballast water discharged by Chinese entry and exit vessels,because of the absence of information platform,and until now there is no public report.Beyond that,there is no effective control measure for NIS invasion risk caused by ballast water discharged to Chinese waters.For the purpose of improving the ballast water management system and protecting the marine ecological environment of China,it is urgent to establish a risk prevention and control emergency treatment technology and device for the ballast water discharged to China.This paper focuses on the risk management and the effective prevention and control of the invasion of marine NIS in China.The volume and features of ballast water discharged by Chinese entry and exit vessels were analyzed in this study.Moreover,the emergency technology and device for ballast water treatment were also investigated.The main research contents and results for this paper are as follows:(1)The loaded and discharged volume of ballast water for Chinese entry and exit vessels were massive with an increasing trend year by year.The volume of ballast water discharged to Chinese waters reached 346 million tons in 2016,while the volume of ballast water loaded in Chinese waters and then discharged to other sea areas reached 957 million tons.Among all port-groups,Yangtze River Delta received the highest volume of foreign ballast water,of which the ratio to that of all ports in China was from 33.57%to 38.98%.The volume of ballast water discharged from Bohai Rim to foreign sea areas was the highest one in China,of which the ratio to that of all ports in China was from 37.31%to 43.32%.The container vessels had the most contribution to the ballast water volume discharged to Chinese waters,while the bulk carriers exported the most volume of ballast water from China.(2)There are more than 97 kinds of suspected NIS transferred to Chinese waters through foreign ballast water,including 29 kinds of red tide organisms in which 15 ones are harmful.(3)A prevention and control method for NIS invasion via ballast water was developed,based on the strong electric field discharge combining with hydrodynamic cavitation technology.When the phytoplankton concentration was 4.92×104 cells/mL,a concentration-time value(CT)of 0.22 mg-min/L could effectively kill the organisms to meet the discharge standard of IMO in 6 s.(4)A 40 tons/hour of portable device for ballast water emergency treatment was developed,based on the prevention and control method for NIS invasion,consisting of high concentration of active particles generating unit and hydrodynamic cavitation unit assembled in a container.The treating capacity of the developed portable equipment ranges from 15 to 40 t/h,while the range of total reactive oxidant(TRO)concentrations is from 0 to 10 mg/L.The field experiments of seawater treatment was carried out with the portable equipment in Dalian Port more than 6 months.Results show that when the phytoplankton concentration was 0.53×103?3.77×104 cells/mL,with a CT value of less than 0.30 mg-min/L,the treating results met the discharge standard of IMO.Meanwhile,the water qualities of seawater were improved obviously.To prevent and control the marine NIS invasion caused by ballast water,the volume and features of ballast water discharged by Chinese entry and exit vessels were analyzed,and the emergency technology and device for ballast water treatment were developed in this paper.The results can serve effective technology and practical device for ballast water management and treatment,which have great significance for the perfection of ballast water management system and the safety of marine ecological environment in China.